Pentaerythritol tetrabenzoate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15.01.2018 - 14.02.2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name: Pentaerythritol tetrabenzoate
Batch no.: D170724-05
Appearance: off-white solid
Composition: Pentaerythritol tetrabenzoate >96%
CAS No.: 4196-86-5
EINECS-No.: 224-079-8
Molecular formula: C33H28O8
Molecular weight: 552.576 g/mol
Purity: >96%
Homogeneity: homogeneous
Expiry date: Nov. 2018
Storage: Room Temperature (20 ± 5°C)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

Activated sludge from a biologic sewage treatment plant was used as inoculum. The chosen plant treats mostly domestic sewage. The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf. Date of collection: 12. Jan. 2018, batch no: 20180112. The sludge was filtrated, washed with test medium (2x) and re-suspended in test medium. It was then aerated until use. The dry matter was determined to contain 4900 mg of suspended solids/L.

Duration of test (contact time):

ca. 28 d

Initial conc.:

>= 28 - <= 28.7 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The medium was prepared from the stock solutions. The stock solution of the positive control was prepared and its DOC was measured. The inoculum was taken from its source, washed, aerated and the dry matter was determined. The test vessels were filled with medium and inoculum. Then, all flasks were aerated for 72 hours with purified, CO2-free, moistened air to purge the system of CO2.

The test vessels were aerated with purified (by activated charcoal), CO2-scrubbed, moistened air. The scrubbing of carbon dioxide was achieved by bubbling the purified air through a flask containing 1.5 M NaOH. To control the absence of CO2, the air was then led through a flask containing a solution of Ba(OH)2 before reaching the test vessels. Magnetic stirrers were used to prevent deposition of inoculum. The emitted CO2 was trapped in 0.25 M NaOH. Two scrubbers containing 100 mL each were connected in series to the test vessels. The initial IC value of the 0.25 M NaOH was separately determined in each flask.

From each front scrubber flask, 10 samples were taken in order to determine the emitted CO2 (on day 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29). The sample volume was 1 mL. The resulting change in the volume of the front flask was considered in the calculation of emitted CO2. On day 28, 5 mL HCl 2 M was added to each test flask in order to drive off dissolved CO2. On day 29, samples from both scrubber flasks were taken.

Reference substance:

aniline

Test performance:

All validity criteria were met.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 3

Sampling time:

28 d

Details on results:

The test item Pentaerythritol tetrabenzoate is considered as “not readily biodegradable“.
The degree of biodegradation reached 3 % after 28 days.
The 10-day-window was not detected.
Degradation missed 60 % within 28 days, too. Therefore, the test item is considered as “not ultimately biodegradable within 28 days”, as well.
The abiotic degradation reached 0.6 %.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item Pentaerythritol tetrabenzoate can be considered as “not readily biodegradable”. Degradation missed 60% within 28 days, though. Therefore, the test item is considered as “not ultimately biodegradable within 28 days”, as well. No observations were made which might cause doubts concerning the validity of the study outcome. The result of the test can be considered valid.

Executive summary:

The test item Pentaerythritol tetrabenzoate (CAS.No.: 4196-86-5) was tested for biodegradation following OECD 301B and Method C.4 -C using a concentration of nominally 20 mg organic carbon/L (corresponding to 27.9 mg Pentaerythritol tetrabenzoate/L) in test medium. Aniline was chosen as positive control. Activated sludge was used as inoculum (concentration in the test 25.0 mg dry matter/L). The test was left running for 28 days. All validity criteria were met. Degradation of the positive control was 80 % after 9 days. The following data were determined for the test item Pentaerythritol tetrabenzoate:

No degradation within the 10 -day-window was detected. Degradation at the end of the test was 3%. Ready biodegradability is defined in the guidelines as degradation surpassing 60% within 10 days after reaching a level of 10 %. Therefore, when applying the 10-day-window, the test item Pentaerythritol tetrabenzoate is not readily biodegradable following OECD 301B and EU C.4-C respectively. As degradation missed 60% in the course of the test, Pentaerythritol tetrabenzoate is considered as not ultimately biodegradable, as well.

Description of key information

The test item Pentaerythritol tetrabenzoate (CAS.No.: 4196-86-5) was tested for biodegradation following OECD 301B and Method C.4 -C using a concentration of nominally 20 mg organic carbon/L (corresponding to 27.9 mg Pentaerythritol tetrabenzoate/L) in test medium. No degradation within the 10 -day-window was detected. Degradation at the end of the test was 3%. When applying the 10-day-window, the test item Pentaerythritol tetrabenzoate is not readily biodegradable following OECD 301B and EU C.4-C respectively. As degradation missed 60% in the course of the test, Pentaerythritol tetrabenzoate is considered as not ultimately biodegradable, as well.